全文获取类型
收费全文 | 3359篇 |
免费 | 400篇 |
国内免费 | 374篇 |
专业分类
电工技术 | 70篇 |
综合类 | 421篇 |
化学工业 | 402篇 |
金属工艺 | 254篇 |
机械仪表 | 106篇 |
建筑科学 | 329篇 |
矿业工程 | 36篇 |
能源动力 | 90篇 |
轻工业 | 77篇 |
水利工程 | 47篇 |
石油天然气 | 49篇 |
武器工业 | 22篇 |
无线电 | 483篇 |
一般工业技术 | 626篇 |
冶金工业 | 91篇 |
原子能技术 | 128篇 |
自动化技术 | 902篇 |
出版年
2024年 | 19篇 |
2023年 | 95篇 |
2022年 | 72篇 |
2021年 | 111篇 |
2020年 | 129篇 |
2019年 | 104篇 |
2018年 | 90篇 |
2017年 | 119篇 |
2016年 | 138篇 |
2015年 | 147篇 |
2014年 | 184篇 |
2013年 | 263篇 |
2012年 | 218篇 |
2011年 | 221篇 |
2010年 | 191篇 |
2009年 | 216篇 |
2008年 | 206篇 |
2007年 | 196篇 |
2006年 | 185篇 |
2005年 | 155篇 |
2004年 | 145篇 |
2003年 | 105篇 |
2002年 | 109篇 |
2001年 | 90篇 |
2000年 | 92篇 |
1999年 | 69篇 |
1998年 | 67篇 |
1997年 | 46篇 |
1996年 | 44篇 |
1995年 | 41篇 |
1994年 | 46篇 |
1993年 | 34篇 |
1992年 | 27篇 |
1991年 | 30篇 |
1990年 | 28篇 |
1989年 | 19篇 |
1988年 | 15篇 |
1987年 | 7篇 |
1986年 | 13篇 |
1985年 | 5篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1959年 | 3篇 |
排序方式: 共有4133条查询结果,搜索用时 0 毫秒
1.
2.
R. A. Borzooei M. Bakhshi M. Mashinchi 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2008,12(8):739-749
In this paper, we study the lattice structure of some fuzzy algebraic systems such as (G-)fuzzy groups, some fuzzy ordered
algebras and fuzzy hyperstructures. We prove that under suitable conditions, these structures form a distributive or modular
lattice.
This research partially is supported by the “ Fuzzy Systems and its Applications Center of Excelence, Shahid Bahonar University
of Kerman, Iran”. 相似文献
3.
Jiang Taihui 《电子科学学刊(英文版)》1996,13(4):325-332
In this paper, an adaptive line spectral pair filter is derived from an adaptive lattice filter. A least-mean-square(LMS) type adaptive algorithm used to calculate directly the line spectral pair(LSP) coefficients on a stage-by-stage basis is presented. Experimental results show that the algorithm has higher convergence rate and lower misadjustment as compared with the other algorithms. The LSP coefficients calculated by the algorithm have been used to carry out speech linear predictive synthesis, resulting in better results than PARCOR coefficients. 相似文献
4.
The compositions (1 −x)Ag2SO4−(x)BaSO4, wherex=0·01 to 0·6, were prepared by slow cooling of the melt. The extent of the solid solubility of Ba2+ in Ag2SO4 was determined by X-ray powder diffraction and scanning electron microscopy. The bulk conductivity of each sample was obtained
using a detailed impedance analysis. The partial substitution of Ba2+ results in the enhancement of conductivity in compliance with the classical aliovalent doping theory. A simplistic model
based on lattice distortion (expansion) due to partial substitution of Ag+ by the bigger Ba2+ has been considered to explain enhanced conductivity. Beyond solid-solubility limit (5·27 mole%) the BaSO4-dispersed Ag2SO4 conductivity follows the usual trend seen in binary systems. An increase in conductivity in this case is discussed in the
light of interfacial reactions and surface defect chemistry. The maximum conductivity in 20 mole% BaSO4 dispersed Ag2SO4 is due to percolation threshold. 相似文献
5.
陈光忠 《计算机应用与软件》1994,11(3):46-53
几何造型是计算机图形学的重要研究内容,CAD/CAM的核心技术,现行的许多造型系统仅限于造型二次曲面及旋转曲面,没有自由曲面造型能力,本文研究的自由畸变为法,很容易扩展这些系统的自由曲面造型功能,该方法已成功地用于扩展MOVIE.BYU系统的自由曲面造型功能。 相似文献
6.
Nucleation kinetics during the growth of InxGa1−xN on a GaN substrate have been studied. The behavior of nonequilibrium between the InxGa1−xN and the GaN substrate has been analyzed, and hence, the expression derived for the stress-induced supercooling/superheating
has been numerically evaluated. The maximum amount of stress-induced supercooling is found to be 1.017 K at x=0.12. These
values are incorporated in the classical heterogeneous nucleation theory. Using the regular solution model, the interfacial
tension between the nucleus and substrate and, hence, the interfacial tension between nucleus and mother phase and thermodynamical
potential of the compounds have been calculated. The amount of driving force available for the nucleation has been determined
for different compositions and degrees of supercooling. It has been shown that the value of the interaction parameter of InN-GaN
plays a dominant role in nucleation and growth kinetics of InxGa1−xN on a GaN substrate. These values have been used to evaluate the nucleation parameters. It is shown that the nucleation barrier
for the formation of a InxGa1−xN nucleus on a GaN substrate is minimum in the range of x=0.12 to x=0.17, and it has been qualitatively proved that good quality
InxGa1−xN on GaN can be grown only in the range 0<x≤0.2. 相似文献
7.
8.
不锈钢网架结构试验研究 总被引:1,自引:1,他引:0
对奥氏体不锈钢网架结构的物理力学性能、焊接性能加以分析,并进行了不锈钢焊接空心球节点承载力试验,确定了该种节点的受拉和受压承载能力。在此基础上,又做了不锈钢组合扭网壳模型的破坏性试验研究,试验结果与理论计算值比较,吻合较好。 相似文献
9.
Besides equidistribution properties and statistical independence the lattice profile, a generalized version of Marsaglia's
lattice test, provides another quality measure for pseudorandom sequences over a (finite) field. It turned out that the lattice
profile is closely related with the linear complexity profile. In this article we give a survey of several features of the
linear complexity profile and the lattice profile, and we utilize relationships to completely describe the lattice profile
of a sequence over a finite field in terms of the continued fraction expansion of its generating function. Finally we describe
and construct sequences with a certain lattice profile, and introduce a further complexity measure. 相似文献
10.
In this note, we show that any distributive lattice is isomorphic to the set of reachable configurations of an Edge Firing Game. Together with the result of James Propp, saying that the set of reachable configurations of any Edge Firing Game is always a distributive lattice, this shows that the two concepts are equivalent. 相似文献